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Some (not uModule) Questions

2001-12-06 by sucrosemusic

Eek!  I need a bit of a break from the uModule discussion.

I've got two questions...  

THE FIRST QUESTION

First off is a technical question that'll sound newbie-ish.  That's 
ok, since I could easily be considered a newbie.  All of my analog 
synths are single VCO based, so I have *zero* experience with hard 
sync.  My understanding is that it's a way of retriggering the wave 
(say sawtooth) even though it may have gone through more or less than 
one oscillation, so you'll get a one-and-a-half cycle wave every 
cycle, or a less-than-one cycle wave every cycle.  Assuming I'm 
right, here's the question:

How do you wire it?

Say I have a 310 uVCO and a 300, can I run the output of the 310 into 
the "hard sync" jack on the 300?  If so, the CV going into the 310 
controls the pitch, whereas the CV going into the 300 only controls 
the timbre of the sound?  (they could both track the main CV i'm 
playing with the coarse adjustment on the 300 set to give me a 
specific sound)

If that's how it works, then great, my understanding is mostly right, 
and I've got lots of interesting hard-sync modulation ideas that I'm 
sure everyone else has been doing since the mid 70s.  <grin>

THE SECOND QUESTION

(pre-addendum [written afterwords, placed in front of]  This is all 
LPF stuff)

I'm looking for a certain aspect to a filter... a certain sound.  Say 
I have a patch that has a very very slow attack and decay, taking 
maybe 10 seconds to creep up and 10 seconds to creep back down.  
That's controlling not just the VCA, but the cutoff on the VCF.  The 
VCF is set to a very high Q, near (or possibly at) self oscillation.  
The sound I'm looking for (and I'm pretty sure I've heard it) is this:

The resonant sound, naer sine wave, of the filter *tracking* the 
harmonic content of the source wave.  So, say if this patch were set 
with no oscillator, and the filter self oscillating, you'd here a 
continuous pitch shift.  That's not what I want.  With the oscillator 
going, I'm looking for that resonant peak to follow the content of 
the wave... so what you hear as the filter's cutoff increases, is the 
resonant sound "jumping" from one frequency to another.  I don't know 
if this is a Roland sound or a moog filter sound or what (maybe it's 
a result of overdriving a filter), but the synth I have uses some CEM 
filter chip or another, and it doesn't seem to do what I want.

Am I just crazy, or does this sound exist? If it does, can I get a 
filter that behaves this way in an MOTM setup?  Will the 440 do it?  
So far, judging from the descriptions and demos, it seems the closest 
one.

I'm pretty sure I'm not crazy about this stepped-plateau effect, I'm 
pretty sure I've heard it in a bunch of slow pad sounds.  Anyway, any 
hints would be great, I *really* need a filter that'll behave this 
way.

Sorry for the UberSpam Longish post, but since I want an MOTM filter 
to do this, this seems like the right place to go.

-Geoff

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